At a location where a global positioning system (GPS) may not be used for measuring a position such as a building or the underground, the pedestrian dead reckoning (PDR) technique is used in order to estimate a position of a pedestrian on an inertial device including an acceleration sensor and a magnetic field sensor.
A conventional method using the PDR estimates a travelling direction and position by calculations executed in the inertial device which is attached and fixed to the body of a user to limit movement of the inertial device (Patent Documents 1 to 4).
On the other hand, a conventional method to estimate the direction and position by high load calculations using data obtained from a high performance inertial sensor (e.g. an acceleration sensor, angular velocity sensor (gyroscope), a magnetic field sensor, etc.) instead of attaching and fixing the inertial device to the body of the user (Patent Documents 5, 6). Such a calculation includes Fourier transformation (FT) or principal component analysis in order to estimate the direction using acceleration or angular velocity obtained by the sensor.
However, the conventional inertial device is inconvenient because the device needs to be fixed to a target (e.g. a user). In addition, since an inertial device which does not need to be fixed has to be high performance, the inertial device tends to be a higher cost, and it is hard to downsize the inertial device.